Hagdon \Hag"don\, n. (Zo["o]l.) One of several species of sea birds of the genus Puffinus; esp., P. major, the greater shearwarter, and P. Stricklandi, the black hagdon or sooty shearwater; -- called also hagdown, haglin, and hag. See Shearwater.

Source: Webster's Revised Unabridged Dictionary (1913)